This invention relates to tools, and in particular to a locking device for tools having a handle portion and a head portion, the head portion being rotably attached to the handle portion such that the head portion may be positioned in a plurality of angular relationships with respect to the handle portion.
Tools having a head portion which may be aligned at various angular dispositions to the handle portion of the tool are well known. For example, in the typical ratchet wrench having a positionable head, the head of the wrench is pivotally attached to the handle by means of a pivot pin. In order to temporarily position the head at a desired location, the head includes a series of detents along an arc in the head and a spring-biased ball is situated in the handle portion, the ball being urged by the spring into one of the detents at a time. When the ball enters a detent, the head portion can be temporarily held at that location. The angle is changed by applying pressure to the face or the back of the head portion to depress the ball against the spring and allow the head to be rotated until the ball engages the next detent in the head.
A disadvantage of such a ratchet wrench is the inability to lock the head securely at a particular orientation. Sufficient pressure applied to the face or back of the head will always cause the head to rotate relative to the handle. Furthermore, as the wrench is used, in time the spring can weaken and the ball and detents become worn. The holding force of the ball/detent arrangement is therefore significantly reduced, and often the head becomes practically free and the wrench essentially useless.
Devices have been devised for locking the head of a rotatable tool, such as a ratchet wrench, in place. For example, U.S. Pat. No. 3,779,106 discloses a ratchet wrench with a series of transverse grooves in the head portion and a rotatable lock pin in the handle portion. The lock pin has one-half of its material removed so that it is semicircular in cross section adjacent the head portion in order that the head may be freely rotated when the flat portion of the lock pin is disposed toward the head portion. When the lock pin is rotated one-half revolution to engage one of the grooves, the head portion is held securely in place.
A disadvantage of this prior art device is its lack of any means to temporarily hold the head portion in place, such as by the ball/detent arrangement described above. The head of the ratchet wrench of U.S. Pat. No. 3,779,106 is either free to rotate without inhibition, or is locked in place.
Other devices have been developed for locking a rotatable tool head in place. For example, European Patent Application No. 80106063.3, filed Oct. 7, 1980, and published Apr. 22, 1981, discloses a wrench having a longitudinally slideable pin arrangement in the handle aligned to engage one of a series of sockets arcuately spaced in the head portion. Similarly, Swiss Pat. No. 243,888 discloses a locking device having a longitudinal pin urged into engagement with one of a series of sockets spaced in an arc in the head of the tool.
Both the Swiss Patent and the European Application suffer from deficiencies similar to U.S. Pat. No. 3,779,107. In both, the head is either locked into place, or is entirely free to rotate. There is no means for temporarily holding the head in combination with the locking device or while the locking device is being engaged.